Systems and methods for purging a chiller system

ABSTRACT

Embodiments of the present disclosure relate to a heating, ventilation, air conditioning, and refrigeration (HVAC&amp;R) system including a refrigerant loop and a purge system configured to purge the HVAC&amp;R system of non-condensable gases. The purge system includes a liquid pump configured to draw a first refrigerant flow from an evaporator, a controllable expansion valve configured to receive the first refrigerant flow from the liquid pump and reduce a temperature of the first refrigerant flow, and a purge heat exchanger, which includes a purge coil. The purge coil is configured to receive the first refrigerant flow from the controllable expansion valve, a chamber of the purge heat exchanger is configured to draw a mixture of the non-condensable gases and a second refrigerant flow from a condenser, and the purge heat exchanger is configured to separate the non-condensable gases from the second refrigerant flow utilizing the first refrigerant flow.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a U.S. National Stage Application of PCT International Application No. PCT/US2018/47780, entitled SYSTEMS AND METHODS FOR PURGING A CHILLER SYSTEM, filed Aug. 23, 2018, which claims priority to U.S. Provisional Application No. 62/718,816, entitled “SYSTEMS AND METHODS FOR PURGING A CHILLER SYSTEM,” filed Aug. 14, 2018, and U.S. Provisional Application No. 62/549,320, entitled “SYSTEMS AND METHODS FOR PURGING A CHILLER SYSTEM,” filed Aug. 23, 2017, which are hereby incorporated by reference in their entireties for all purposes.

BACKGROUND

This application relates generally to purging systems for air conditioning and refrigeration applications.

Chiller systems, or vapor compression systems, utilize a working fluid, such as a refrigerant, that changes phases between vapor, liquid, and combinations thereof in response to exposure to different temperatures and pressures associated with operation of the vapor compression system. In low-pressure chiller systems, some components of the low-pressure chiller systems operate at a lower pressure than the surrounding atmosphere. Due to the pressure differential, non-condensable gases (NCG), such as ambient air, may migrate into these low-pressure components, which may cause inefficiencies in the low-pressure chiller system. Accordingly, the low-pressure chiller system may be purged of the NCG to run more effectively. However, traditional purge systems used to remove the NCG may be costly, require excessive maintenance, and may have inefficiencies.

SUMMARY

In an embodiment of the present disclosure, a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a refrigerant loop, a compressor disposed along the refrigerant loop, an evaporator disposed along the refrigerant loop, and a condenser disposed along the refrigerant loop. The compressor is configured to circulate refrigerant through the refrigerant loop, the evaporator is configured to place the refrigerant in a heat exchange relationship with a first cooling fluid, and the condenser is configured to place the refrigerant in a heat exchange relationship with second cooling fluid. The HVAC&R system also includes a purge system configured to purge the HVAC&R system of non-condensable gases (NCG). The purge system includes a liquid pump configured to draw a first refrigerant flow from the evaporator, a controllable expansion device configured to receive the first refrigerant flow from the liquid pump and reduce a temperature of the first refrigerant flow, and a purge heat exchanger. The purge heat exchanger includes a purge coil. The purge coil is configured to receive the first refrigerant flow from the controllable expansion device, a chamber of the purge heat exchanger is configured to draw in a mixture including the non-condensable gases and a second refrigerant flow from the condenser, and the purge heat exchanger is configured to separate the non-condensable gases of the mixture from the second refrigerant flow of the mixture utilizing the first refrigerant flow.

In another embodiment of the present disclosure, a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a refrigerant loop, a compressor disposed along the refrigerant loop, an evaporator disposed along the refrigerant loop, and a condenser disposed along the refrigerant loop. The compressor is configured to circulate refrigerant through the refrigerant loop, the evaporator is configured to place the refrigerant in a heat exchange relationship with a first cooling fluid, and the condenser is configured to place the refrigerant in a heat exchange relationship with second cooling fluid. The HVAC&R system also includes a purge system configured to purge the HVAC&R system of non-condensable gases (NCG). The purge system includes a purge heat exchanger configured to separate a mixture drawn from the condenser utilizing a first refrigerant flow of the refrigerant drawn from the evaporator. The mixture includes the NCG and a second refrigerant flow of the refrigerant from the condenser. Separating the mixture includes separating the NCG from the second refrigerant flow. The purge system also includes one or more thermoelectric assemblies configured to remove thermal energy from the second refrigerant flow.

In another embodiment of the present disclosure, a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a refrigerant loop, a compressor disposed along the refrigerant loop, an evaporator disposed along the refrigerant loop, and a condenser disposed along the refrigerant loop. The compressor is configured to circulate refrigerant through the refrigerant loop, the evaporator is configured to place the refrigerant in a heat exchange relationship with a first cooling fluid, and the condenser is configured to place the refrigerant in a heat exchange relationship with second cooling fluid. The HVAC&R system also includes a purge system configured to purge the HVAC&R system of non-condensable gases (NCG). The purge system includes one or more adsorption chambers configured to receive a mixture including the refrigerant and the NCG from the condenser and configured to separate the refrigerant from the NCG. The purge system also includes a pump configured to draw the mixture from the condenser.

In a further embodiment of the present disclosure, a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a purge system configured to purge a vapor compression system of non-condensable gases (NCG). The purge system includes a pump configured to draw a mixture of vapor refrigerant and the NCG from a condenser of the vapor compression system. The purge system further includes a purge heat exchanger configured to receive the mixture from the pump and place the mixture in a heat exchange relationship with a refrigerant flow drawn from the vapor compression system to condense the vapor refrigerant of the mixture and separate the NCG of the mixture from the vapor refrigerant. The pump is configured to increase a pressure of the mixture to induce flow of the NCG from the purge heat exchanger into the atmosphere via a pressure differential between the NCG and the atmosphere.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of an embodiment of a building that may utilize a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system in a commercial setting, in accordance with an aspect of the present disclosure;

FIG. 2 is a perspective view of an embodiment of an HVAC&R system, in accordance with an aspect of the present disclosure;

FIG. 3 is a schematic of an embodiment of the HVAC&R system of FIG. 2, in accordance with an aspect of the present disclosure;

FIG. 4 is a schematic of an embodiment of the HVAC&R system of FIG. 2, in accordance with an aspect of the present disclosure;

FIG. 5 is a schematic of an embodiment of the HVAC&R system of FIG. 2, in accordance with an aspect of the present disclosure;

FIG. 6 is a schematic of an embodiment of the HVAC&R system of FIG. 2, in accordance with an aspect of the present disclosure;

FIG. 7 is a schematic of an embodiment of the HVAC&R system of FIG. 2, in accordance with an aspect of the present disclosure;

FIG. 8 is a schematic of an embodiment of the HVAC&R system of FIG. 2, in accordance with an aspect of the present disclosure; and

FIG. 9 is a schematic of an embodiment of the HVAC&R system of FIG. 2, in accordance with an aspect of the present disclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure include a purge system that may improve an efficiency of purging in a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system. For example, in certain low-pressure HVAC&R systems an evaporator may draw in non-condensable gases (NCG), such as ambient air from the atmosphere, due to a pressure differential between the evaporator and the atmosphere. The NCG may travel through the HVAC&R system to ultimately collect within the condenser. The NCG may be detrimental to the overall performance of the HVAC&R system and, as such, should be removed. Accordingly, the presently-disclosed embodiments may efficiently purge the HVAC&R system of the NCG. To this end, the HVAC&R system may include the purge system that may direct a first flow of refrigerant from the evaporator to an additional heat exchanger and then utilize the first flow of refrigerant to separate the NCG from a second flow of refrigerant of the HVAC&R system that may have accumulated within the condenser by condensing the second flow of refrigerant to separate the NCG from the second flow of refrigerant. Thereafter, the NCG may be pumped out or otherwise released to atmosphere. Additionally, or in the alternative, the purge system may utilize one or more other systems in addition to the additional heat exchanger for purging the HVAC&R system of the NCG. For example, the purge system may also utilize one or more thermoelectric assemblies and/or adsorption chambers. Specifically, the one or more thermoelectric assemblies may help to reduce a temperature of the refrigerant directed from the evaporator to help with the heat exchange process within the additional heat exchanger. Further, the one or more adsorption chambers may filter the refrigerant from the NCG by utilizing an adsorptive material with an electrochemical affinity for refrigerant, which will adsorb the refrigerant and allow the NCG to flow out of the HVAC&R system. Moreover, in certain embodiments, the purge system may utilize a vapor pump to draw the NCG and the second flow of refrigerant from the condenser and deliver the NCG and the second flow of refrigerant to the additional heat exchanger. That is, the vapor pump may increase a pressure of the NCG and the second flow of refrigerant as it is delivered to the additional heat exchanger. Due to the higher pressure, the second flow of refrigerant may condense at a higher temperature within the additional heat exchanger, thereby reducing a load on the purge system.

Turning now to the drawings, FIG. 1 is a perspective view of an embodiment of an environment for a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system 10 in a building 12 for a typical commercial setting. The HVAC&R system 10 may include a vapor compression system 14 that supplies a chilled liquid, which may be used to cool the building 12. The HVAC&R system 10 may also include a boiler 16 to supply warm liquid to heat the building 12 and an air distribution system which circulates air through the building 12. The air distribution system can also include an air return duct 18, an air supply duct 20, and/or an air handler 22. In some embodiments, the air handler 22 may include a heat exchanger that is connected to the boiler 16 and the vapor compression system 14 by conduits 24. The heat exchanger in the air handler 22 may receive either heated liquid from the boiler 16 or chilled liquid from the vapor compression system 14, depending on the mode of operation of the HVAC&R system 10. The HVAC&R system 10 is shown with a separate air handler on each floor of building 12, but in other embodiments, the HVAC&R system 10 may include air handlers 22 and/or other components that may be shared between or among floors.

FIGS. 2 and 3 are embodiments of the vapor compression system 14 that can be used in the HVAC&R system 10. The vapor compression system 14 may circulate a refrigerant through a circuit starting with a compressor 32. The circuit may also include a condenser 34, an expansion valve(s) or device(s) 36, and a liquid chiller or an evaporator 38. The vapor compression system 14 may further include a control panel 40 (e.g., controller) that has an analog to digital (A/D) converter 42, a microprocessor 44, a non-volatile memory 46, and/or an interface board 48.

Some examples of fluids that may be used as refrigerants in the vapor compression system 14 are hydrofluorocarbon (HFC) based refrigerants, for example, R-410A, R-407, R-134a, hydrofluoro-olefin (HFO), “natural” refrigerants like ammonia (NH₃), R-717, carbon dioxide (CO₂), R-744, or hydrocarbon based refrigerants, water vapor, refrigerants with low global warming potential (GWP), or any other suitable refrigerant. In some embodiments, the vapor compression system 14 may be configured to efficiently utilize refrigerants having a normal boiling point of or above about 0 degrees Celsius or 32 degrees Fahrenheit at one atmosphere of pressure, also referred to as low-pressure refrigerants, versus a medium-pressure refrigerant, such as R-134a, or high pressure refrigerants such as R-410A. As used herein, “normal boiling point” may refer to a boiling point temperature measured at one atmosphere of pressure.

In some embodiments, the vapor compression system 14 may use one or more of a variable speed drive (VSDs) 52, a motor 50, the compressor 32, the condenser 34, the expansion valve or device 36, and/or the evaporator 38. The motor 50 may drive the compressor 32 and may be powered by a variable speed drive (VSD) 52. In certain embodiments, the compressor 32 may utilize magnetic bearings. The VSD 52 receives alternating current (AC) power having a particular fixed line voltage and fixed line frequency from an AC power source, and provides power having a variable voltage and frequency to the motor 50. In other embodiments, the motor 50 may be powered directly from an AC or direct current (DC) power source. The motor 50 may include any type of electric motor that can be powered by a VSD or directly from an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or another suitable motor.

The compressor 32 compresses a refrigerant vapor and delivers the vapor to the condenser 34 through a discharge passage. In some embodiments, the compressor 32 may be a centrifugal compressor. The refrigerant vapor delivered by the compressor 32 to the condenser 34 may transfer heat to a cooling fluid (e.g., water or air) in the condenser 34. The refrigerant vapor may condense to a refrigerant liquid in the condenser 34 as a result of thermal heat transfer with the cooling fluid. The refrigerant liquid from the condenser 34 may flow through the expansion device 36 to the evaporator 38. In the illustrated embodiment of FIG. 3, the condenser 34 is water cooled and includes a tube bundle 54 connected to a cooling tower 56, which supplies the cooling fluid to the condenser.

The refrigerant liquid delivered to the evaporator 38 may absorb heat from another cooling fluid, which may or may not be the same cooling fluid used in the condenser 34. The refrigerant liquid in the evaporator 38 may undergo a phase change from the refrigerant liquid to a refrigerant vapor. As shown in the illustrated embodiment of FIG. 3, the evaporator 38 may include a tube bundle 58 having a supply line 60S and a return line 60R connected to a cooling load 62. The cooling fluid of the evaporator 38 (e.g., water, ethylene glycol, calcium chloride brine, sodium chloride brine, or any other suitable fluid) enters the evaporator 38 via return line 60R and exits the evaporator 38 via supply line 60S. The evaporator 38 may reduce the temperature of the cooling fluid in the tube bundle 58 via thermal heat transfer with the refrigerant. The tube bundle 58 in the evaporator 38 can include a plurality of tubes and/or a plurality of tube bundles. In any case, the refrigerant vapor exits the evaporator 38 and returns to the compressor 32 by a suction line to complete the cycle.

FIG. 4 is a schematic of the vapor compression system 14 with an intermediate circuit 64 incorporated between condenser 34 and the expansion device 36. The intermediate circuit 64 may have an inlet line 68 that is directly fluidly connected to the condenser 34. In other embodiments, the inlet line 68 may be indirectly fluidly coupled to the condenser 34. As shown in the illustrated embodiment of FIG. 4, the inlet line 68 includes a first expansion device 66 positioned upstream of an intermediate vessel 70. In some embodiments, the intermediate vessel 70 may be a flash tank (e.g., a flash intercooler). In other embodiments, the intermediate vessel 70 may be configured as a heat exchanger or a “surface economizer.” In the illustrated embodiment of FIG. 4, the intermediate vessel 70 is used as a flash tank, and the first expansion device 66 is configured to lower the pressure of (e.g., expand) the refrigerant liquid received from the condenser 34. During the expansion process, a portion of the liquid may vaporize, and thus, the intermediate vessel 70 may be used to separate the vapor from the liquid received from the first expansion device 66. Additionally, the intermediate vessel 70 may provide for further expansion of the refrigerant liquid because of a pressure drop experienced by the refrigerant liquid when entering the intermediate vessel 70 (e.g., due to a rapid increase in volume experienced when entering the intermediate vessel 70). The vapor in the intermediate vessel 70 may be drawn by the compressor 32 through a suction line 74 of the compressor 32. In other embodiments, the vapor in the intermediate vessel may be drawn to an intermediate stage of the compressor 32 (e.g., not the suction stage). The liquid that collects in the intermediate vessel 70 may be at a lower enthalpy than the refrigerant liquid exiting the condenser 34 because of the expansion in the expansion device 66 and/or the intermediate vessel 70. The liquid from intermediate vessel 70 may then flow in line 72 through a second expansion device 36 to the evaporator 38.

In some embodiments, when the vapor compression system 14 is in operation, the evaporator 38 may function at a pressure that is lower than the ambient pressure. As such, NCG may be drawn into the evaporator 38 and move through the compressor 32 to gather in the condenser 34. These NCG may cause the vapor compression system 14 to operate inefficiently. Accordingly, the vapor compression system 14 may include features to purge the vapor compression system 14 of the NCG.

For example, as seen in FIG. 5, the vapor compression system 14 may include a purge system 80. The purge system 80 is configured to remove NCG such as ambient air from the vapor compression system 14 by utilizing refrigerant from the vapor compression system 14. To this end, in certain embodiments the purge system 80 may include a flash tank 82, a liquid pump 84, a controllable expansion device 86, a purge heat exchanger 88, a pump 90 (e.g., a vacuum pump and/or a vapor pump), an ejector 94, and one or more stop valves 96, such as solenoid valves.

First, it should be noted that in the following description, the refrigerant may be referred to as having a low, medium, and/or high temperature and/or pressure. Indeed, the low, medium, and high pressure/temperature descriptions of the refrigerant refer to relative pressure/temperature values of the same refrigerant within the vapor compression system 14 and/or purge system 80. In other words, the vapor compression system may use a single refrigerant type that may have different pressure values throughout the vapor compression system 14 and/or purge system 80.

In some embodiments, the vapor compression system 14 may utilize a controller 81 to control certain aspects of operation of the purge system 80. The controller 81 may be any device employing a processor 83 (which may represent one or more processors), such as an application-specific processor. The controller 81 may also include a memory device 85 for storing instructions executable by the processor 83 to perform the methods and control actions described herein for the purge system 80. The processor 83 may include one or more processing devices, and the memory 85 may include one or more tangible, non-transitory, machine-readable media. By way of example, such machine-readable media can include RAM, ROM, EPROM, EEPROM, CD-ROM, or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by the processor 83 or by any general purpose or special purpose computer or other machine with a processor.

To this end, the controller 81 may be communicatively coupled one or more components of the purge system 80 through a communication system 87. In some embodiments, the communication system 87 may communicate through a wireless network (e.g., wireless local area networks [WLAN], wireless wide area networks [WWAN], near field communication [NFC]). In some embodiments, the communication system 87 may communicate through a wired network (e.g., local area networks [LAN], wide area networks [WAN]). For example, as shown in FIGS. 5 and 6, the controller 81 may communicate to a number of elements of the purge system 80 such as pumps, valves, expansion devices, and other components. In some embodiments, functions of the controller 81 and the control panel 40 (FIGS. 3 and 4) as described herein may be controlled through a single controller. In some embodiments, the single controller may be the control panel 40 or the controller 81.

As shown in FIG. 5, the liquid pump 84 may draw refrigerant (e.g., a first refrigerant flow) from the evaporator 38 through a conduit 98. The refrigerant drawn from the evaporator 38 may have a medium pressure (e.g., approximately 5 pounds per square inch absolute [psia]) and a medium temperature (e.g., approximately 40 degrees Fahrenheit). In some embodiments, the refrigerant may be a two-phase mixture including mostly refrigerant liquid with some portion of refrigerant vapor. Accordingly, in some embodiments, the refrigerant may first flow to the flash tank 82 before flowing to the liquid pump 84 to separate the two-phase mixture. Indeed, in some embodiments, the purge system 80 may not utilize the flash tank 82. Within the flash tank 82, the two-phase mixture may separate with the refrigerant liquid accumulating at the bottom of the flash tank 82 and the refrigerant vapor gathering at the top of the flash tank 82 due to density differences. The liquid pump 84 may then pull the refrigerant liquid from the bottom of the flash tank 82 through a conduit 100. As the refrigerant travels from the flash tank 82 to the pump 84, the refrigerant may have a medium temperature (e.g., approximately 40 degrees Fahrenheit) and a medium pressure (e.g., approximately 5 psia). The accumulated refrigerant vapor in the flash tank 82 may be pulled through a conduit 102 to the evaporator 38. Specifically, the refrigerant vapor from the flash tank 82 may flow to a low-pressure, or outlet, side of the evaporator 38. For example, the pressure differential between the low-pressure side of the evaporator 38 and the flash tank 82 may draw the refrigerant vapor from the flash tank 82 into the suction side of the evaporator 38. Indeed, the conduit 102 may be designed (e.g., sized, shaped, textured, etc.) such that the refrigerant flowing through the conduit 102 remains at a high enough pressure to flow into the evaporator 38. As the refrigerant vapor flows from the flash tank 82 to the evaporator 38, the refrigerant vapor may have a medium temperature (e.g., approximately 40 degrees Fahrenheit) and a medium pressure (e.g., approximately 5 psia).

The pump 84 may force the refrigerant liquid through a conduit 104 to the controllable expansion device 86. As the refrigerant liquid travels from the liquid pump 84 to the controllable expansion device 86, the refrigerant liquid may have a medium temperature (e.g., approximately 45 degrees Fahrenheit) and a high pressure (e.g., approximately 16 psia). Indeed, the refrigerant liquid exiting the liquid pump 84 may have a higher pressure and temperature relative to the refrigerant entering the liquid pump 84. Further, the controller 81 may send one or more liquid pump signals to the liquid pump 84 to control the mass flow rate of refrigerant through the liquid pump 84.

As the refrigerant travels through the controllable expansion device 86, the controllable expansion device 86 may decrease the pressure of the refrigerant and, therefore, also decrease the temperature. In some embodiments, the controllable expansion device 86 may be disposed vertically above the purge heat exchanger 88. After exiting the controllable expansion device 86, the refrigerant may travel through a conduit 106 to a purge coil 108 of the purge heat exchanger 88 due at least in part to the height differential between the controllable expansion valve 86 and the purge heat exchanger 88. As the refrigerant travels from the controllable expansion device 86 to the purge heat exchanger 88, the refrigerant may have a low temperature (e.g., approximately 6 degrees Fahrenheit) and a low pressure (e.g., approximately 3.5 psia). Further, in some embodiments, as the controllable expansion device 86 decreases the pressure of the refrigerant, some portion of the refrigerant may boil off as refrigerant vapor.

As discussed in further detail below, as the refrigerant travels through the purge coil 108 of the purge heat exchanger 88, the refrigerant may exchange heat with a mixture of refrigerant vapor (e.g., a second refrigerant flow) and NCG that have been pulled from the condenser 34 or from another part of the system. As mentioned above, due to the low pressures of the vapor compression system 14 relative to ambient pressures while in operation, the NCG may be drawn into the evaporator 38 and travel through the vapor compression system 14 to accumulate in the condenser 34. Specifically, the NCG may accumulate in a portion of the condenser 34. Accordingly, the mixture of the NCG and the refrigerant vapor may be pulled from the portion of the condenser 34. Generally, during normal operation, the portion in which the NCG accumulate may be substantially below a discharge baffle, near the middle of the condenser 34, near an outlet of the condenser 34, near a top of the condenser 34, or any combination thereof.

In some embodiments, the NCG that have accumulated in the condenser 34 may be mixed with refrigerant vapor. The NCG and refrigerant vapor mixture may be drawn through a conduit 114 into the purge heat exchanger 88, such as a chamber of the purge heat exchanger 88. The NCG and refrigerant vapor mixture may be drawn into the purge heat exchanger 88 due to the pressure differential between the condenser 34 and the purge heat exchanger 88. Moreover, in certain embodiments, the NCG and vapor mixture may be drawn into the purge heat exchanger 88 due to a partial vacuum in the purge heat exchanger 88 caused by condensation within the purge heat exchanger 88.

As the NCG and refrigerant vapor mixture comes into contact with the low temperature surface of the purge coil 108, the refrigerant vapor will condense into refrigerant liquid and create a partial vacuum within the purge heat exchanger 88, thereby drawing in more of the NCG and refrigerant vapor mixture from the condenser 34 through the conduit 114. Further, as the NCG and refrigerant vapor mixture enters the purge heat exchanger 88 and the refrigerant vapor condenses into refrigerant liquid, the refrigerant liquid will gather in the bottom of the purge heat exchanger 88. Indeed, due at least partially to a density difference between the condensed refrigerant liquid and the NCG, the NCG will collect towards the top of the purge heat exchanger 88, while the condensed refrigerant liquid will collect at the bottom of the purge heat exchanger 88. Accordingly, as more of the refrigerant vapor of the NCG and refrigerant vapor mixture condenses within the purge heat exchanger 88, a liquid level of the refrigerant liquid within the purge heat exchanger 88 will rise.

As described in further detail below, once the liquid level of the refrigerant liquid has reached a predetermined threshold in the purge heat exchanger 88, the refrigerant liquid will be drained through a conduit 115 to the condenser 34, the evaporator 38, or both, and the NCG will be pumped out of the purge heat exchanger 88 by the pump 90 through a conduit 116. In some embodiments, the purge heat exchanger 88 may be disposed vertically above the condenser 34 and the evaporator 38. In this manner, the refrigerant liquid may flow to the condenser 34, the evaporator 38, or both, due at least in part to the height differential of the purge heat exchanger 88 relative to the condenser 34 and the evaporator 38. In some embodiments, the condenser 34 may be disposed vertically above the evaporator 38, thereby allowing the refrigerant liquid to flow more easily to the evaporator 38 relative to the condenser 34 from the purge heat exchanger 88. Further, the pump 90 may expel the NCG into the atmosphere as shown by arrow 117.

In some embodiments, the purge heat exchanger 88 may include one or more sensors 119, which may include one or more temperature sensors, pressure sensors, weight sensors, liquid level sensors, ultrasonic sensors, or any combination thereof. For example, one sensor 119 of the one or more sensors 119 may measure the liquid level of the refrigerant liquid within the purge heat exchanger 88 and send data regarding the liquid level to the controller 81. If the liquid level is approaching, matching, and/or exceeding the predetermined liquid level threshold, the controller 81 may send a signal to one or more of the stop valves 96 to allow the refrigerant liquid to drain to the condenser 34, the evaporator 38, or both, as described above. Similarly, the controller 81 may send a signal to the pump 90 and/or one or more of the stop valves 96 to release the NCG through the pump 90 into the atmosphere.

In some embodiments, the controller 81 may determine whether there is a significant or predetermined amount of NCG within the condenser 34 before allowing the NCG and refrigerant vapor mixture to enter the purge heat exchanger 88, such as by activating one or more of the stop valves 96. To determine whether there is a significant or predetermined amount of NCG within the condenser 34, another sensor 119 of the one or more sensors 119 may measure one or more parameters related to a performance of the vapor compression system 14 and send data indicative of the one or more parameters to the controller 81 to analyze and process. Specifically, the controller 81 may determine a performance of the vapor compression system 14 based on the one or more parameters. If the controller 81 determines that the performance of the vapor compression system 14 is below a predetermined threshold, the controller 81 may allow the condenser 34 to be purged as described above by opening an appropriate stop valve and allowing the mixture of NCG and refrigerant vapor to flow to the purge heat exchanger 88 from the condenser 34. In some embodiments, the controller 81 may purge the condenser 34 as described above based on a predetermined schedule.

Additionally, or in the alternative, one of the sensors 119 may measure a saturation temperature and an actual temperature within the condenser 34 and send data indicative of the saturation and actual temperatures to the controller 81 to analyze and process. The controller 81 may then determine whether the saturation temperature substantially matches the actual temperature. If the saturation temperature does not substantially match the actual temperature, the controller 81 may allow the condenser 34 to be purged as described above by opening an appropriate stop valve 96 and allowing the mixture of NCG and refrigerant vapor to flow to the purge heat exchanger 88 from the condenser 34.

Furthermore, as mentioned above, the refrigerant traveling through the purge coil 108 of the purge heat exchanger 88 may exchange heat with the mixture of refrigerant vapor and NCG that has been pulled from the condenser 34. More specifically, the refrigerant traveling through the purge coil 108 may absorb thermal energy from the mixture of the refrigerant vapor and NCG and undergo a phase change from liquid to vapor and exit the purge coil 108 through a conduit 118 to the ejector 94. Indeed, the refrigerant vapor exiting the purge coil 108 may be a superheated vapor with a medium temperature (e.g., approximately 30 degrees Fahrenheit) and a low pressure (e.g., approximately 3.5 degrees psia).

To condense the refrigerant vapor pulled from the condenser 34, the refrigerant entering the purge coil 108 may be at an adequately low temperature. To this end, another sensor 119 of the one or more sensors 119 may measure a temperature of the refrigerant entering the purge coil 108 and send data indicative of the temperature of the refrigerant to the controller 81 to analyze and process. In this manner, the controller 81 may control (e.g., further open and/or close) the controllable expansion device 86 to adjust the temperature of the refrigerant flowing into the purge coil 108 to achieve the adequately low temperature.

After exiting the purge coil 108, the refrigerant vapor may be pulled into the ejector 94 due to a pressure differential relative to a stream of refrigerant vapor that may enter the ejector 94 through a conduit 120 from the condenser 34. The ejector 94 may also help to pull refrigerant through the expansion device 86 and the purge coil 108. More specifically, high-pressure refrigerant vapor from the condenser 34 may enter the ejector 94 through a nozzle 122 and increase in flow velocity and decrease in pressure as it flows through the nozzle 122. In this manner, the now low-pressure refrigerant vapor exiting the nozzle 122 may draw the refrigerant vapor from the purge coil 108, thereby mixing the high pressure refrigerant vapor from the condenser 32 and the refrigerant vapor from the purge coil 108 within the ejector 94. As the refrigerant vapors mix within the ejector 94, they will travel through the ejector 94 and exit through a diffuser cone 124 of the ejector 94. Further, the refrigerant vapors will mix as it travels through the ejector 94, which may lead to a decrease in velocity and an increase in pressure. As the refrigerant vapor moves through the diffuser cone 124, the diffuser cone 124 will further reduce the flow velocity and increase the pressure of the refrigerant vapor exiting the ejector 94. The refrigerant vapor exiting the ejector 94 may then be routed through a conduit 126 to the low-pressure side of the evaporator 38. More specifically, the refrigerant vapor exiting the ejector 94 is drawn into the evaporator 38 due to the pressure differential relative to the lower-pressure refrigerant within the evaporator 38. Particularly, the refrigerant flowing from the ejector 94 to the evaporator 38 may be at a medium temperature (e.g., approximately 40 degrees Fahrenheit) and a medium pressure (e.g., approximately 5 psia).

As mentioned above, the embodiments described with respect to FIG. 5 may be utilized when the vapor compression system 14 is in operation. Indeed, while in operation, the low pressures within the vapor compression system 14 may draw in ambient air and/or other non-condensable gases. While the vapor compression system 14 is not in operation however, the vapor compression system 14 may still contain some amount of residual NCG, particularly in an upper portion of the condenser 34. However, while the vapor compression system 14 is not in operation, the ejector 94 may not pull in high-pressure refrigerant from the condenser 34 to pull the refrigerant from the purge coil 108 because pressure levels of the refrigerant within the vapor compression system 14 may level out while the vapor compression system 14 is not in operation. Accordingly, as shown in FIG. 6, the purge system 80 may utilize thermoelectric assemblies 150 and/or adsorption chambers 152 to purge the vapor compression system 14 of the residual NCG.

For example, as shown in FIG. 6, when the vapor compression system 14 is not in operation, the liquid pump 84 may draw in refrigerant from the evaporator 38 through the conduit 100. The liquid pump 84 may then pump the refrigerant through the conduit 104 to the purge coil 108 of the purge heat exchanger 88 through the controllable expansion valve 86. While traveling from the liquid pump 84 to the purge coil 108, the refrigerant may decrease in temperature as the thermoelectric assemblies 150 absorb heat from the refrigerant and release the heat to the surrounding atmosphere. Specifically, the thermoelectric assemblies 150 may utilize a power source 154 to induce an electrical power gradient within the thermoelectric assemblies 150. The power source 154 may be any suitable power source including, but not limited to: a power grid, a battery, a solar panel, an electrical generator, a gas engine, the vapor compression system 14, or any combination thereof. The thermoelectric assemblies 150 may convert the electrical power gradient to a thermal gradient through the thermoelectric effect, or Peltier-Seebeck effect. Particularly, the thermoelectric assemblies 150 may utilize the thermal gradient to absorb heat from the refrigerant flowing from the liquid pump 84 to the purge coil 108.

In the current embodiment, the thermoelectric assemblies 150 are disposed on the conduit 104 between the liquid pump 84 and the controllable expansion valve 86 and are configured to absorb heat from the refrigerant as it flows through the conduit 104. However, in some embodiments, the thermoelectric assemblies 150 may be disposed on the conduit 106 between the controllable expansion valve 106 and the purge coil 108 and may be configured to absorb heat from the refrigerant as it flows through the conduit 106. In some embodiments, the conduit 104 and/or 106 may be thermally insulated. Specifically, a thermoelectric assembly 150 a, or thermoelectric module, of the thermoelectric assemblies 150 may include thermal paste 156, a thermoelectric device 158, a heat sink 160, and a fan 162. For example, the thermoelectric assembly 150 a is coupled to a conduit, such as the conduit 104 and/or the conduit 106, with the thermal paste 156, which may be coupled to a first side of the thermoelectric device 158. A second side of the thermoelectric device 158 is coupled to the heat sink 160, which is in turn coupled to the fan 162. The thermoelectric assemblies 150 may include any suitable number of individual thermoelectric assemblies 150 a, or thermoelectric modules. For example, in some embodiments, the purge system 80 may include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or any other suitable number of thermoelectric assemblies 150 a. In some embodiments, the conduit on which the thermoelectric assemblies 150 are coupled to, such as the conduit 104 and/or the conduit 106, may include internal fins 161 to promote heat transfer to the thermoelectric assemblies 150.

As the thermoelectric assemblies 150 absorb heat from the refrigerant, the refrigerant may become subcooled. Accordingly, the controllable expansion valve 86 may be completely or substantially opened (e.g., as directed by the controller 81) such that none, or minimal amounts, of the refrigerant boils off (e.g., the refrigerant remains subcooled) before it reaches the purge coil 108. As the subcooled refrigerant travels through the purge coil 108, the subcooled refrigerant may exchange heat with the mixture of NCG and refrigerant vapor that may have been pulled into the purge heat exchanger 88 from the condenser 34, as described above in reference to FIG. 5. However, unlike the embodiments described above in FIG. 5, it should be noted that, in some embodiments, the subcooled refrigerant traveling through the purge coil 108 may be subcooled enough such that the subcooled refrigerant substantially, if not completely, remains in the liquid state as it travels through the purge coil 108 and absorbs heat from the mixture of NCG and refrigerant vapor. In some embodiments, the fluid pump 84 may force the subcooled refrigerant through the purge coil 108 at such a high flow rate (e.g., as directed by the controller 81) such that the subcooled refrigerant substantially, if not completely, remains in the liquid state as it travels through the purge coil 108 and absorbs heat from the mixture of NCG and refrigerant vapor. In some embodiments, to ensure that the refrigerant remains in the liquid state as it travels through the purge coil 108, the controller 81 may send a signal to one or more of the stop valves 96 and the liquid pump 84, such that the thermoelectric assemblies 150 are in a heat exchange relationship with the refrigerant for an extended period of time, thereby further reducing the temperature of the refrigerant before it flows into the purge coil 108.

Due at least in part to the liquid state of the refrigerant within the purge coil 108, a head pressure and/or gravity may enable the refrigerant to flow back to the evaporator 38 through a conduit 163. Further, as described above, the refrigerant vapor of the mixture of NCG and refrigerant vapor pulled from the condenser 34 may condense and gather in the bottom of the purge heat exchanger 88 and eventually flow back to condenser 34 and/or the evaporator 38 once the refrigerant fluid level reaches a predetermined threshold within the purge heat exchanger 88.

Also as shown in FIG. 6, in some embodiments, the purge system 80 may utilize the adsorption chambers 152 to purge the vapor compression system 14 of ambient air or other non-condensable gases. For example, in some embodiments, the NCG gas/refrigerant vapor that the pump 90 pulls from the purge heat exchanger 88 may contain some portion of refrigerant vapor along with NCG. Accordingly, the adsorption chambers 152 may remove the portion of refrigerant vapor drawn in by the pump 90 before expelling the NCG into the atmosphere. To illustrate, the pump 90 may pump the mixture of NCG and refrigerant vapor, or “mixture”, through a conduit 164 to one or more of the adsorption chambers 152. As the mixture traverses through an adsorption chamber 152 of the adsorption chambers 152, the mixture may be passed through a modified material 166 of the adsorption chamber 152 and the refrigerant vapor may be adsorbed, or attracted, into and/or onto the modified material 166 due to the properties of the modified material 166 and the refrigerant vapor. For example, electrochemical properties aid in adsorption as described herein. Further, as the mixture traverses through the adsorption chamber 152, the NCG may not be adsorbed into the modified material 166 also due at least in part to the properties of the NCG and the modified material 166. Accordingly, the NCG may pass through the modified material 162 and continue through an air outlet valve 168 as shown by arrows 170 to be expelled into the atmosphere.

As the modified material 166 adsorbs the refrigerant, the modified material 166 may eventually become saturated with the refrigerant and may no longer efficiently adsorb additional refrigerant. Accordingly, heaters 169, such as immersion heaters, outer cable heaters, or band heaters, may be activated to provide thermal energy to the modified material 166. The modified material 166 transfers the thermal energy to the refrigerant. Over time, the thermal energy imparted to the refrigerant will cause the bonds of the modified material 166 the refrigerant to be overcome such that the modified material 166 releases the refrigerant in a vapor state. Once released from the modified material 166, the refrigerant vapor may have a high pressure relative to pressures within the evaporator 38 such that the refrigerant vapor flows to the evaporator 38 through a conduit 170. In some embodiments, the adsorption chambers 152 may utilize a vacuum pump to create a pulling force at outlets of the adsorption chambers 152. The pulling force may be stronger than the electrochemical bonds of the modified material 166 and the refrigerant such that the refrigerant is pulled from the modified material 166.

In some embodiments, the inlet valves 166 may allow the mixture to flow to only certain adsorption chambers 152 at a time. In this manner, the adsorption chambers 152 may continuously receive and filter the mixture as described above. For example, the controller 81 may control the stop valves 96 to allow the mixture to be filtered by one or more specific adsorption chambers 152 of the adsorption chambers 152. Once the specific adsorption chamber 152 becomes saturated with the refrigerant, the controller 81 may stop flow of the mixture to the specific adsorption chamber 152 and allow the mixture to flow to a different adsorption chamber 152. Once the controller 81 has stopped flow to the specific adsorption chamber 152, the controller may activate the heater 169 associated with the specific adsorption chamber 152 to allow the refrigerant vapor to flow to the evaporator 38 as described above. Indeed, while the specific adsorption chamber 152 is being heated, the different adsorption chamber 152 may continue to filter the mixture. Once the specific adsorption chamber 152 is sufficiently unsaturated with the refrigerant, the controller 81 may once again activate one or more of the stop valves 96 to allow the mixture to flow the specific adsorption chamber 152. To this end, the purge system 80 may include 1, 2, 3, 4, 5, 6, or any other suitable number of individual adsorption chambers 152 to allow continuous filtration of the mixture. Further, it should be noted that embodiments discussed herein with respect to FIG. 6, specifically the utilization of the thermoelectric assemblies 150 and/or the adsorption chambers 152, may be utilized if the vapor compression system 14 is in operation or if the vapor compression system 14 is not in operation.

In certain embodiments, as shown in FIG. 7, the purge system 80 may utilize a pump 202, such as a reciprocal/diaphragm oil-free vapor pump, disposed upstream of the purge heat exchanger 88, that is configured to increase a pressure of the mixture before the mixture enters the purge heat exchanger 88. In this manner, the temperature at which the vapor refrigerant of the mixture condenses in the purge heat exchanger 88 is increased, thereby reducing a load on the purge system 80. Moreover, the purge system 80 may include a solenoid valve 204, an ejector 206, such as the ejector 94, the purge heat exchanger 88, which may be a shell and tube heat exchanger, and one or more stop valves 96.

Generally, the purge system 80 may utilize refrigerant from the vapor compression system 14 to purge the vapor compression system 14 of NCG. In other words, refrigerant from the vapor compression system 14 may be used as a cooling source for condensing the refrigerant and NCG mixture within the purge system 80. For example, the purge system 80 may draw the mixture of NCG and vapor refrigerant from the condenser 34. The mixture is then pumped to the purge heat exchanger 88, where the vapor refrigerant is condensed, thereby separating the refrigerant of the mixture from the NCG of the mixture. Particularly, to condense the vapor refrigerant, the mixture is placed in a heat exchange relationship with refrigerant pulled from downstream of the expansion device 36 of the vapor compression system 14. The condensed refrigerant is then drained to the condenser 34, and the NCG is released into the atmosphere.

To further illustrate, the pump 202 may draw the mixture of vapor refrigerant and NCG from the condenser 34 through a conduit 203. In certain embodiments, the mixture drawn from the condenser 34 may be approximately 94° F. and 26 psi. The pump 202 may raise a pressure of the mixture as it pumps the mixture from the condenser 34 and delivers the mixture through a conduit 205 to the purge heat exchanger 88. In certain embodiments, the pump 202 may raise the pressure of the mixture by approximately 50 psi. For example, after passing through the pump 202, the mixture may be approximately 160° F. and 76 psi and may be a superheated vapor with a flow rate of approximately 10 lbm/hr (pounds-mass per hour). Due to the increased pressure, the refrigerant vapor within the mixture will condense at higher heat exchange temperatures within the purge heat exchanger 88, as mentioned above. That is, as the pump 202 raises the pressure of the mixture, the condensation temperature of the vapor refrigerant correspondingly rises, and therefore the vapor refrigerant will utilize less cooling to condense. In certain embodiments, the pump 202 may raise the pressure of the mixture such that the vapor refrigerant may condense at approximately 43° F. within the purge heat exchanger 88. In certain embodiments, the pump 202 may include two pumps 199 disposed in series with one another. In this manner, the load is split or divided between the two pumps 199, which may result in less stress induced on the individual pumps 199, thereby resulting in less maintenance of the pumps 199.

As the purge heat exchanger 88 condenses the vapor refrigerant into liquid refrigerant, the liquid refrigerant may gather in the base of the purge heat exchanger 88. As discussed above, once the liquid refrigerant reaches a threshold volume within the purge heat exchanger 88, the controller 81 may operate the stop valves 96 to drain the liquid refrigerant from the purge heat exchanger 88 and to the condenser 34 through a conduit 207. In certain embodiments, the liquid refrigerant may be continuously drained to the condenser 34. In certain embodiments, the liquid refrigerant drained from the purge heat exchanger 88 may be a subcooled liquid at approximately 160° F. and 76 psi.

Moreover, as the refrigerant and the NCG are separated within the purge heat exchanger 88, the NCG may be released into the atmosphere through the solenoid valve 204 via a conduit 209. For example, the pump 202 may raise the pressure of the mixture entering the purge heat exchanger 88, such that the pressure of the NCG separated from the refrigerant in the mixture is greater than the atmospheric pressure. Accordingly, the pressure differential between the NCG in the purge heat exchanger 88 and the atmosphere may drive the flow of NCG through the solenoid valve 204 and into the atmosphere. In some embodiments, the controller 81 may activate the solenoid valve 204 to release the NCG into the atmosphere once a fluid level within the purge heat exchanger 88 reaches a threshold value. In certain embodiments, the controller 81 may block the mixture from entering the purge heat exchanger 88, such as by actuating one or more of the stop valves 96 and/or deactivating the pump 202, prior to releasing the NCG through the solenoid valve 204. In this manner, the purge system 80 may ensure that substantially all of the vapor refrigerant of the mixture within the purge heat exchanger 88 has condensed, thereby blocking release of vapor refrigerant through the solenoid valve 204.

As discussed above, the vapor refrigerant and NCG of the mixture may be separated within the purge heat exchanger 88 as the vapor refrigerant condenses into liquid refrigerant. Particularly, to condense the vapor refrigerant, the mixture may be placed in a heat exchange relationship with liquid refrigerant drawn from the vapor compression system 14. More specifically, the liquid refrigerant may be drawn from the vapor compression system 14 refrigerant loop downstream of the expansion device 36 through a conduit 211. As discussed herein, the refrigerant that is drawn from the refrigerant loop of the vapor compression system 14 at a location downstream of expansion device 36 and is used to condense the vapor refrigerant of the mixture may be referred to as the “expanded refrigerant.” The expanded refrigerant may be substantially liquid, and/or may contain some flash gas.

To condense the vapor refrigerant of the mixture within the purge heat exchanger 88, the expanded refrigerant may be routed through tubes 210 of the purge heat exchanger 88. As the expanded refrigerant travels through the tubes 210 of the purge heat exchanger 88, the expanded refrigerant may exchange heat with the mixture. Particularly, the expanded refrigerant may absorb heat from the mixture. Accordingly, as the expanded refrigerant exits the tubes 210 of the purge heat exchanger 88, the expanded refrigerant may be a superheated vapor. For example, the expanded refrigerant may exit the purge heat exchanger 88 at approximately 43° F. and 9 psi with a flow rate of approximately of 8.5 lbm/hr.

To draw the expanded refrigerant through the tubes 210 of the purge heat exchanger 88, the purge system 80 may utilize the ejector 206. The ejector 206 may function similarly to the ejector 94, as described above. For example, the ejector 206 may utilize a pressure differential to draw the expanded refrigerant through the tubes 210 of the purge heat exchanger 88 and through a conduit 212. Specifically, the ejector 206 may utilize refrigerant drawn through a conduit 213 fluidly coupled to a location along the refrigerant loop of the vapor compression system 14 that is directly downstream of the compressor 32, such as between the compressor 32 and the condenser 34. The ejector 206 may function with increased performance due at least in part to a low pressure differential between the expanded refrigerant flowing through the tubes 210 and the refrigerant drawn from the refrigerant loop downstream of the compressor 32. For example, a pressure of the expanded refrigerant drawn from the tubes 210 may be approximately between 8 psi and 9 psi, and a pressure the refrigerant drawn from downstream of the compressor 32 may be approximately 26 psi. The ejector 206 may then flow the combined refrigerant through a conduit 215 to the evaporator 38. Further, the liquid refrigerant may flow from the purge heat exchanger 88 to the evaporator 38 due at least in part to a height differential between the purge heat exchanger 88 and the evaporator 38. Additionally, or in the alternative, the liquid refrigerant may flow from the purge heat exchanger 88 to the condenser 34 due at least in part to a height differential between the purge heat exchanger 88 and the condenser 34.

Further, in certain embodiments, such as the embodiment shown in FIG. 8, the purge system 80 may utilize a liquid pump 222, such as the liquid pump 84, to draw refrigerant from the evaporator 38 to condense the vapor refrigerant of the mixture within the purge heat exchanger 88. Moreover, the purge system 80 may utilize the pump 202, such as a reciprocal/diaphragm oil-free vapor pump, the solenoid valve 204, the purge heat exchanger 88, which may be a direct contact heat exchanger, the pump 202, the liquid pump 222, and one or more stop valves 96, to purge the vapor compression system 14 of NCG.

Generally, the purge system 80 may utilize refrigerant drawn from the vapor compression system 14 to purge the vapor compression system 14 of NCG. For example, the purge system 80 may draw the NCG, which may be mixed with vapor refrigerant, from the condenser 34. The mixture of NCG and vapor refrigerant is then pumped to the purge heat exchanger 88, where the vapor refrigerant is condensed, thereby separating the refrigerant of the mixture from the NCG of the mixture. Particularly, to condense the vapor refrigerant, the mixture is placed in a heat exchange relationship with refrigerant, which may be drawn from the evaporator 38 or from a location along the vapor compression system 14 refrigerant loop upstream of the expansion device 36. The condensed refrigerant within the purge heat exchanger 88 is then drained to the evaporator 38 and/or the condenser 34, and the NCG is released into the atmosphere.

To further illustrate, the pump 202 may draw the mixture of refrigerant vapor and NCG from the condenser 34 through the conduit 203. In certain embodiments, the mixture drawn from the condenser 34 may be approximately 94° F. and 26 psi. The pump 202 may raise a pressure of the mixture as it pumps the mixture from the condenser 34 and delivers the mixture through the conduit 205 to the purge heat exchanger 88. In certain embodiments, the pump 202 may raise the pressure of the mixture by approximately 50 psi. Particularly, after passing through the pump 202, the mixture may be a superheated vapor. For example, the mixture may be approximately 160° F. and 76 psi with a flow rate of approximately 10 lbm/hr (pounds-mass per hour). In this manner, the refrigerant vapor will condense at higher heat exchange temperatures within the purge heat exchanger 88. That is, as the pump 202 raises the pressure of the mixture, the condensation temperature of the refrigerant correspondingly rises and therefore utilizes less cooling to condense.

Once pumped into the purge heat exchanger 88, the mixture may exchange heat with refrigerant drawn from the evaporator 38 and/or from upstream of the expansion device 36. More specifically, the liquid pump 222 may draw liquid refrigerant through a conduit 223 from a bottom, or flooded, section of the evaporator 38, raise the pressure of the liquid refrigerant, and deliver the liquid refrigerant to the purge heat exchanger 88 through a conduit 225 to exchange heat with the mixture. The liquid refrigerant drawn from the evaporator 38 may be approximately 43° F. and 9 psi, and may be a subcooled liquid. The liquid pump 222 may increase the pressure of the liquid refrigerant, such as to approximately 76 psi, and may deliver the liquid refrigerant in a subcooled state to the purge heat exchanger 88 at approximately 30 lbm/hr. Moreover, it should be noted that the output pressure of the mixture through the pump 202 may substantially match the output pressure of the liquid refrigerant exiting the liquid pump 222. Indeed, the pump 202 may deliver the mixture to the purge heat exchanger 88 at approximately 160° F. and 76 psi with a flow rate of approximately 10 lbm/hr.

In some embodiments, the liquid pump 222 may draw the liquid refrigerant from upstream of the expansion valve 36, as discussed above. In such embodiments, the liquid pump 222 may function with increased efficiency due to a decreased pressure differential. For example, the liquid refrigerant upstream of the expansion device 36 may be at a higher pressure than liquid refrigerant of the evaporator 38. Therefore, to match the pressure output of the pump 202, the liquid pump 222 may have to work less if the liquid pump 222 is pumping liquid refrigerant drawn from upstream of the expansion device 36.

The liquid refrigerant drawn from the evaporator 38 and/or from upstream of the expansion device 36 may be supplied to the purge heat exchanger 88 through a spray system 224, which may include spray nozzles and a sprayer rack configured to disperse the liquid refrigerant throughout the inner volume of the purge heat exchanger 88. As the liquid refrigerant mixes with the mixture of vapor refrigerant and NCG, the vapor refrigerant of the mixture may condense into liquid refrigerant, which may then form a pool of liquid refrigerant in the bottom of the purge heat exchanger 88. The liquid refrigerant may then be drained to the evaporator 38, as shown, through a conduit 226. For example, as discussed above, once the liquid refrigerant reaches a threshold volume within the purge heat exchanger 88, the controller 81 may operate the stop valves 96 to drain the liquid refrigerant to the evaporator 38. In certain embodiments, the liquid refrigerant may be continuously drained to the evaporator 38 and/or to the condenser 34. In certain embodiments, the liquid refrigerant drained from the purge heat exchanger 88 may be a subcooled liquid at approximately 132° F. and 76 psi.

Moreover, as the refrigerant and the NCG of the mixture are separated within the purge heat exchanger 88, the NCG may be released into the atmosphere through the solenoid valve 204. For example, the pump 202 may raise the pressure of the vapor refrigerant and NCG mixture such that the pressure of the NCG within the purge heat exchanger 88 is greater than the atmospheric pressure. Accordingly, the pressure differential between the NCG in the purge heat exchanger 88 and the atmosphere may drive the flow of NCG through the solenoid valve 204 into the atmosphere. In some embodiments, the controller 81 may activate the solenoid valve 204 to release the NCG into the atmosphere once a fluid level of the purge heat exchanger 88 reaches a threshold value. In certain embodiments, the controller 81 may block the mixture from entering the purge heat exchanger 88, such as by actuating one or more stop valves and/or deactivating the pump 202, prior to releasing the NCG through the solenoid valve 204. In this manner, the purge system 80 may ensure that substantially all of the vapor refrigerant of the mixture within the purge heat exchanger 88 has condensed, thereby blocking release of vapor refrigerant through the solenoid valve 204. Further, the liquid refrigerant may flow from the purge heat exchanger 88 to the evaporator 38 due at least in part to a height differential between the purge heat exchanger 88 and the evaporator 38. Additionally, or in the alternative, the liquid refrigerant may flow from the purge heat exchanger 88 to the condenser 34 due at least in part to a height differential between the purge heat exchanger 88 and the condenser 34.

As discussed above, in certain embodiments, the pump 202 may include two pumps 199 disposed in series. In this manner, the load is split between the two pumps 199, which may result in less stress induced on each individual pump 199, thereby resulting in less maintenance of the pumps 199. Similarly, in certain embodiments, the liquid pump 222 may include two liquid pumps 227 disposed in series. In this manner, the load is split between the two liquid pumps 227, which may result in less stress induced on each individual liquid pump 227, thereby resulting in less maintenance of the liquid pumps 227.

Additionally, the embodiments discussed with reference to FIG. 8 above may be utilized while the vapor compression system 14 is off Indeed, as discussed with reference to the embodiments of FIG. 8, the purge system 80 may not necessarily utilize the conditions produced by the vapor compression system 14 during operation. That is, the pump 202 and the liquid pump 222 may induce the pressures utilized by functions of the purge system 80 to purge the vapor compression system 14 of NCG.

Further, in certain embodiments, as shown in FIG. 9, the purge system 80 may draw refrigerant from the refrigerant loop of the vapor compression system 14 upstream of the expansion device 36 to condense the vapor refrigerant of the mixture. Particularly, the purge system 80 may utilize a second expansion device 230 to expand the refrigerant to an intermediate pressure between pressures of the condenser 34 and the evaporator 38, such that the pressure differential drives a flow of the refrigerant through the tubes 210 of the purge heat exchanger 88. Moreover, the purge system 80 may utilize the pump 202, the purge heat exchanger 88, such as a shell and tube heat exchanger, the solenoid valve 204, and a three-way valve 228, to remove the NCG, which may have accumulated in the condenser 34, as discussed above.

Generally, the purge system 80 may utilize refrigerant drawn from the vapor compression system 14 to purge the vapor compression system 14 of NCG. For example, the purge system 80 may draw the NCG, which may be disposed in a mixture with vapor refrigerant, from the condenser 34. The mixture is then pumped to the purge heat exchanger 88, where the vapor refrigerant is condensed, thereby separating the refrigerant of the mixture from the NCG of the mixture. For example, to condense the vapor refrigerant, the mixture is placed in a heat exchange relationship with refrigerant drawn from upstream of the expansion device 36. The condensed refrigerant is then drained to the condenser 34, and the NCG is released into the atmosphere.

To further illustrate, the pump 202 may draw the mixture of refrigerant vapor and NCG from the condenser 34 through the conduit 203. In certain embodiments, the mixture drawn from the condenser 34 may be approximately 94° F. and 26 psi. The pump 202 may raise a pressure of the mixture as it pumps the mixture from the condenser 34 and delivers the mixture through the conduit 205 to the purge heat exchanger 88. In certain embodiments, the pump 202 may raise the pressure of the mixture by approximately 50 psi. For example, after passing through the pump 202, the mixture may be a superheated vapor at approximately 160° F. and 76 psi with a flow rate of approximately 10 lbm/hr (pounds-mass per hour). In this manner, the refrigerant vapor within the mixture may more easily condense within the purge heat exchanger 88. That is, as the pump 202 raises the pressure of the mixture, the condensation temperature of the refrigerant correspondingly rises and therefore utilizes less cooling to condense.

As the purge heat exchanger 88 condenses the vapor refrigerant into liquid refrigerant, the liquid refrigerant may gather in the base of the purge heat exchanger 88. As discussed above, once the liquid refrigerant reaches a threshold volume within the purge heat exchanger 88, the controller 81 may operate the stop valves 96 to drain the liquid refrigerant to the condenser 34 through the conduit 207. In certain embodiments, the liquid refrigerant may be continuously drained to the condenser 34. In certain embodiments, the liquid refrigerant drained from the purge heat exchanger 88 may be a subcooled liquid at approximately 160° F. and 76 psi.

Moreover, as the vapor refrigerant and the NCG of the mixture are separated within the purge heat exchanger 88, the NCG may be released into the atmosphere through the solenoid valve 204 via the conduit 209. For example, the pump 202 may raise the pressure of the NCG and vapor refrigerant mixture such that the pressure of the NCG within the purge heat exchanger 88 is greater than the atmospheric pressure. Accordingly, the pressure differential between the NCG in the purge heat exchanger 88 and the atmosphere may drive the flow of NCG through the solenoid valve 204 into the atmosphere. In some embodiments, the controller 81 may activate the solenoid valve 204 to release the NCG into the atmosphere once an internal pressure of the purge heat exchanger 88 reaches a threshold value. In certain embodiments, the controller 81 may block the mixture from entering the purge heat exchanger 88, such as by actuating one or more stop valves 96 and/or deactivating the pump 202, prior to releasing the NCG through the solenoid valve. In this manner, the purge system 80 may ensure that substantially all of the vapor refrigerant of the mixture within the purge heat exchanger 88 has condensed, thereby blocking release of vapor refrigerant through the solenoid valve 204.

To condense the vapor refrigerant of the mixture, the purge system 80 may place the mixture in a heat exchange relationship with liquid refrigerant within the purge heat exchanger 88. The liquid refrigerant may be drawn from the refrigerant loop of the vapor compression system 14 at a location upstream of the expansion device 36 and through the three-way valve 228. Prior to entering the purge heat exchanger 88, the liquid refrigerant drawn from the refrigerant loop may be expanded, via the second expansion device 230, to an intermediate pressure. Particularly, the intermediate pressure may be above a pressure of the evaporator 38 and below a pressure of the condenser 34. For example, the intermediate pressure may be at approximately between 9 psi and 26 psi. As another example, the intermediate pressure may be approximately 10 psi to 12 psi while the pressure of the evaporator 38 may be approximately 9 psi. Therefore, the liquid refrigerant may flow through the tubes 210 of the purge heat exchanger 88, vaporize, and flow to the evaporator 38 through a conduit 238 due at least in part to the pressure differential between the vapor refrigerant and the evaporator 38. For example, after exiting the purge heat exchanger 88, the vapor refrigerant may be approximately 52° F. and 11 psi, while the refrigerant within the evaporator 38 may be approximately 9 psi. Further, the vapor refrigerant may flow from the purge heat exchanger 88 to the evaporator 38 due at least in part to a height differential between the purge heat exchanger 88 and the evaporator 38. Additionally, or in the alternative, the vapor refrigerant may flow from the purge heat exchanger 88 to the condenser 34 due at least in part to a height differential between the purge heat exchanger 88 and the condenser 34.

Further, as shown in FIGS. 5-9, in some embodiments, pumps, such as the liquid pump 84, the pump 90, the pump 202, and/or the liquid pump 222 may be powered by one or more motors 180, which may be any suitable motor. In some embodiments, the controller 81 may control the pumps through communication with the one or more motors 180. In some embodiments, the one or more motors 180 may receive power from a power source 154, which may be similar to the power source 154 used to power the thermoelectric assemblies 150.

Accordingly, the present disclosure is directed to systems and methods for purging a low-pressure HVAC&R system (e.g., chiller system, vapor compression system) of NCG that may have entered the HVAC&R system during operation. Specifically, a purge system may purge the HVAC&R system of NCG by utilizing refrigerant drawn from the HVAC&R system. In other words, a first flow of the refrigerant of the HVAC&R system mixed with the NCG may be purged of the NCG utilizing a second flow of the refrigerant of the HVAC&R system as a cooling source to condense the first flow of refrigerant and separate the first flow of refrigerant from the NCG. The disclosed embodiments are cost efficient relative to traditional purging methods and enable the HVAC&R system to be purged of the NCG without using an additional refrigerant loop with additional refrigerant.

While only certain features and embodiments have been illustrated and described, many modifications and changes may occur to those skilled in the art (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters (e.g., temperatures, pressures, etc.), mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention. Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described (i.e., those unrelated to the presently contemplated best mode of carrying out the invention, or those unrelated to enabling the claimed invention). It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation. 

1. A heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, comprising: a refrigerant loop; a compressor disposed along the refrigerant loop, wherein the compressor configured to circulate refrigerant through the refrigerant loop; an evaporator disposed along the refrigerant loop, wherein the evaporator is configured to place the refrigerant in a heat exchange relationship with a first cooling fluid; a condenser disposed along the refrigerant loop, wherein the condenser is configured to place the refrigerant in a heat exchange relationship with second cooling fluid; and a purge system configured to purge the HVAC&R system of non-condensable gases, the purge system comprising: a liquid pump configured to draw a first refrigerant flow from the evaporator; an controllable expansion valve configured to receive the first refrigerant flow from the liquid pump and reduce a temperature of the first refrigerant flow; and a purge heat exchanger comprising a purge coil, wherein the purge coil is configured to receive the first refrigerant flow from the controllable expansion valve, wherein a chamber of the purge heat exchanger is configured to draw a mixture comprising the non-condensable gases and a second refrigerant flow from the condenser, and wherein the purge heat exchanger is configured to separate the non-condensable gases of the mixture from the second refrigerant flow of the mixture utilizing the first refrigerant flow.
 2. The HVAC&R system of claim 1, comprising an ejector configured to receive the first refrigerant flow from the purge coil, wherein the ejector is configured to increase the pressure of first refrigerant flow utilizing the second refrigerant flow from the condenser.
 3. The HVAC&R system of claim 2, wherein the evaporator is configured to receive the second refrigerant flow and the first refrigerant flow discharged from the ejector.
 4. The HVAC&R system of claim 1, wherein the purge system further comprises a pump configured to remove the non-condensable gases of the mixture from the purge heat exchanger.
 5. The HVAC&R system of claim 1, wherein the purge system further comprises a conduit configured to flow the first refrigerant flow from the liquid pump to the controllable expansion valve, and wherein one or more thermoelectric assemblies are coupled to the conduit and configured to remove thermal energy from the first refrigerant flow flowing through the conduit.
 6. The HVAC&R system of claim 5, wherein each thermoelectric assembly of the one or more thermoelectric assemblies is configured to remove thermal energy of the first refrigerant flow by converting an electrical power gradient to a thermal gradient.
 7. The HVAC&R system of claim 1, wherein the purge system further comprises one or more adsorption chambers configured to receive the mixture from the purge heat exchanger, and wherein each adsorption chamber of the one or more adsorption chambers is configured to separate the non-condensable gases of the mixture from the second refrigerant flow of the mixture.
 8. The HVAC&R system of claim 7, wherein the one or more adsorption chambers is configured to expel the non-condensable gases of the mixture into the atmosphere and flow the second refrigerant flow of the mixture to the evaporator.
 9. The HVAC&R system of claim 1, wherein the liquid pump is configured to draw the first refrigerant flow from the evaporator through a flash tank, wherein the first refrigerant flow drawn from the evaporator comprises refrigerant liquid and refrigerant vapor, and wherein the flash tank is configured to separate the refrigerant liquid from the refrigerant vapor.
 10. The HVAC&R system of claim 9, wherein the flash tank is configured to flow the refrigerant liquid to the liquid pump and flow refrigerant vapor to the evaporator.
 11. The HVAC&R system of claim 1, wherein the purge heat exchanger is configured to flow the second refrigerant flow of the mixture into the condenser, the evaporator, or both.
 12. A heating, ventilation, air conditioning, and refrigeration (HVAC&R) system comprising: a refrigerant loop; a compressor disposed along the refrigerant loop and configured to circulate refrigerant through the refrigerant loop; an evaporator disposed along the refrigerant loop and configured to place the refrigerant in a heat exchange relationship with a first cooling fluid; a condenser disposed along the refrigerant loop and configured to place the refrigerant in a heat exchange relationship with a second cooling fluid; and a purge system configured to purge the HVAC&R system of non-condensable gases (NCG), the purge system comprising: a purge heat exchanger configured to separate a mixture drawn from the condenser utilizing a first refrigerant flow of the refrigerant drawn from the evaporator, wherein the mixture comprises the NCG and a second refrigerant flow of the refrigerant from the condenser, and wherein separating the mixture comprises separating the NCG from the second refrigerant flow; and one or more thermoelectric assemblies configured to remove thermal energy from the second refrigerant flow.
 13. The HVAC&R system of claim 12, wherein the purge system further comprises a liquid pump configured to draw the first refrigerant flow from the evaporator and push the first refrigerant flow through the one or more thermoelectric assemblies to the purge heat exchanger.
 14. The HVAC&R system of claim 13, wherein the purge system further comprises a conduit configured to flow the first refrigerant flow from the liquid pump to the purge heat exchanger, and wherein the one or more thermoelectric assemblies are coupled to the conduit.
 15. The HVAC&R system of claim of claim 14, wherein each thermoelectric assembly of the one or more thermoelectric assemblies comprises: thermal paste configured to couple the thermoelectric assembly to the conduit; a thermoelectric assembly coupled to the thermal paste and configured to remove thermal energy from the first refrigerant flow by converting an electrical power gradient to a thermal gradient; a heat sink coupled to the thermoelectric assembly; and a fan coupled to the heat sink.
 16. The HVAC&R system of claim 12, wherein the purge heat exchanger comprises a purge coil configured to receive the first refrigerant flow.
 17. The HVAC&R system of claim 12, wherein the purge system further comprises a pump configured to remove the NCG from the purge heat exchanger.
 18. The HVAC&R system of claim 12, wherein the purge heat exchanger is configured to flow the second refrigerant flow to the condenser, the evaporator, or both.
 19. The HVAC&R system of claim 12, wherein the purge system further comprises one or more adsorption chambers configured to receive at least a portion of the mixture from the purge heat exchanger, and wherein the one or more adsorption chambers is configured to separate the second refrigerant flow from the NCG by adsorbing the second refrigerant flow.
 20. A heating, ventilation, air conditioning, and refrigeration (HVAC&R) system comprising: a refrigerant loop; a compressor disposed along the refrigerant loop and configured to circulate refrigerant through the refrigerant loop; an evaporator disposed along the refrigerant loop and configured to place the refrigerant in a heat exchange relationship with a first cooling fluid; a condenser disposed along the refrigerant loop and configured to place the refrigerant in a heat exchange relationship with second cooling fluid; and a purge system configured to purge the HVAC&R system of non-condensable gases (NCG), the purge system comprising: a purge heat exchanger configured to separate a mixture drawn from the condenser utilizing a first refrigerant flow of the refrigerant drawn from the evaporator, wherein the mixture comprises the NCG and a second refrigerant flow of the refrigerant from the condenser, and wherein separating the mixture comprises separating the NCG from the second refrigerant flow; and one or more adsorption chambers configured to receive the NCG from the purge heat exchanger, wherein the one or more adsorption chambers is configured to separate the NCG from remaining refrigerant.
 21. The HVAC&R system of claim 20, wherein each of the one or more adsorption chambers comprises a modified material configured to adsorb the remaining refrigerant and allow the NCG to pass through the one or more adsorption chambers.
 22. The HVAC&R system of claim 21, wherein each of the one or more adsorption chambers comprises a heater configured to heat the modified material to expel the remaining refrigerant from the modified material.
 23. The HVAC&R system of claim 20, wherein the evaporator is configured to receive the remaining refrigerant from the one or more adsorption chambers.
 24. The HVAC&R system of claim 20, wherein the one or more adsorption chambers is configured to expel the NCG into the atmosphere.
 25. The HVAC&R system of claim 20, wherein the purge system further comprises: a pump configured to draw the NCG from the purge heat exchanger, wherein the one or more adsorption chambers is configured to receive the NCG from the pump; a liquid pump configured to draw the first refrigerant flow from the evaporator; a controllable expansion valve configured to receive the first refrigerant flow from the liquid pump and decrease a pressure of the first refrigerant flow; and a purge coil of the purge heat exchanger configured to receive the first refrigerant flow from the controllable expansion valve; wherein a chamber of the purge heat exchanger enables the mixture to exchange heat with the first refrigerant flow within the purge coil.
 26. The HVAC&R system of claim 25, wherein the purge system further comprises one or more thermoelectric assemblies configured to remove thermal energy from the first refrigerant flow exiting the liquid pump by converting an electrical power gradient into a thermal gradient.
 27. A heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, comprising: a purge system configured to purge a vapor compression system of non-condensable gases (NCG), comprising: a pump configured to draw a mixture, comprising vapor refrigerant and the NCG, from a condenser of the vapor compression system; and a purge heat exchanger configured to receive the mixture from the pump and place the mixture in a heat exchange relationship with a refrigerant flow drawn from the vapor compression system to condense the vapor refrigerant of the mixture and separate the NCG of the mixture from the vapor refrigerant, wherein the pump is configured to increase a pressure of the mixture to induce flow of the NCG from the purge heat exchanger into the atmosphere via a pressure differential between the NCG and the atmosphere.
 28. The HVAC&R system of claim 27, comprising a liquid pump configured to draw the refrigerant flow from the vapor compression system and provide the refrigerant flow to the purge heat exchanger.
 29. The HVAC&R system of claim 28, wherein the purge heat exchanger is a direct contact heat exchanger.
 30. The HVAC&R system of claim 27, comprising an expansion device disposed along a conduit extending from a refrigerant loop of the vapor compression system to the purge heat exchanger, wherein the conduit and the expansion device are configured to supply the refrigerant flow to the purge heat exchanger.
 31. The HVAC&R system of claim 30, wherein the expansion device is configured to lower a pressure of the refrigerant flow to induce flow of the refrigerant flow through the purge heat exchanger and back to the vapor compression system via a second pressure differential between the refrigerant flow and an evaporator of the vapor compression system.
 32. The HVAC&R system of claim 27, comprising an ejector configured to draw the refrigerant flow from the purge heat exchanger and direct the refrigerant flow to an evaporator of the vapor compression system. 